By Steven Spotswood
WASHINGTON—The VA treats about a million veterans for diabetes, nearly one-fourth of its patient population.
At the same time, a recent study found that more than 40,000 veterans 75 and older were diagnosed between 2002 and 2012 with AFib, which occurs more frequently with age, and that 34% of them also were diagnosed with diabetes.1
That’s why new information on the nexus of AFib and diabetes is critically important to VA healthcare professionals.
The significance is further magnified when the research appearing in the Journal of the American College of Cardiology (JACC) suggests that the risk of ischemic stroke is even greater than previously suspected in patients with both conditions and that the length of time since diabetes was diagnosed is a more important indicator of risk than many other factors, including glucose control.2
“One of the critical questions has been what leads to the stroke in patients with atrial fibrillation and diabetes,” explained Valentin Fuster, MD, PhD, JACC editor-in-chief, in a commentary on the recent study. “Is it duration of diabetes, the intensity of treatment reflected in part by hemoglobin A1c, or is it other factors?”
The study provided the following answer to that question: For patients who have suffered from diabetes for at least three years and who also have AFib, the risk of ischemic stroke rose by about 75%. The increase was independent of the age of the patient and, in a surprising turn of events, quality of hemoglobin A1c control seemed to have no effect on the stroke risk.
Duration of diabetes might be important, according to the authors, because the longer a patient suffers from diabetes, the more likely the disease will affect blood clotting. Previous studies have found that prolonged duration of diabetes significantly increases thrombin generation, which can heighten the risk of thrombosis.
According to the authors, accounting for duration of diabetes could improve stroke risk models in patients with AFib. While presence of diabetes is currently one of the major risk factors for stroke, duration has not been taken into account.
In some ways, the VA, with its older patient population, has been ahead of the game in grappling with AFib and comorbidities. An estimated 70% of AFib patients are between the ages of 65 and 85.
VA physicians come across patients with AFib at a rate several times that of civilian primary care physicians. For VA cardiologists, treating AFib has become routine. So has taking into account the comorbidities that plague older veterans.
“This is something so, so common,” said Steven Singh, MD, chief of cardiology at the DC VAMC. “Older people are very likely to get atrial fibrillation. I see it all the time.”
Singh is quick to note that it’s not the irregular heartbeat of AFib itself that’s so dangerous, but the way the irregularity causes blood to collect in the heart. That increases the risk of blood clots, which can lead to stroke.
VA has more than 6,000 admissions for ischemic stroke every year and, according to researchers, AFib is at least partially to blame for between 14% and 36% of them.
When determining an AFib patient’s stroke risk, comorbid conditions play a strong role—something measured in the CHADS2 (congestive heart failure, hypertension, age>75 years, diabetes, stroke) score. A check mark next to any of these factors raises the score and increases the patient’s chance of suffering ischemic stroke.
While comorbid conditions don’t limit treatment options necessarily, they increase the urgency of treating AFib. “If you have high BP or diabetes, your ability to form clots increases tremendously,” Singh told U.S. Medicine. “If you have a high CHADS2 score, you need cardiac electroversion.”
Of course, that’s not an option for all patients.
“If the AFib keeps recurring, quite often this will lead to chronic AFib, and at times we leave the patient in AFib,” he added. That might be the treatment decision for older veterans in nursing homes who are prescribed blood thinners to prevent stroke but are not subjected to more-aggressive treatment.
Warfarin has been found to reduce the threat of a thromboembolic stroke in high-risk patients by nearly two-thirds.
Yet, in terms of older adults living in the community, VA physicians often are wary of prescribing warfarin for a variety of reasons. A recent study in JAMA Cardiology found that the rate of traumatic intracranial bleeding among older adults with AF initiating warfarin therapy actually was higher than previously reported in clinical trials. A conference presentation the year before reported that more than 1 in 5 older veterans were hospitalized for bleeding following initiation of warfarin for atrial fibrillation.3
Target specific oral anticoagulants (TSOAs) might hold some promise for resolving these issues. They don’t require regular INR testing, and the lack of INR variability might lower bleeding risk, according to the JAMA Cardiology researchers.
Dabigatran, the first of the TSOAs, which also now include rivaroxaban and apixaban, was approved in 2010. Patient, physicians and pharmacists were at first hesitant to adopt widespread use of therapies, especially in older patients, because of the risk of bleeding and the lack of a specific antidote, but those concerns are lessening. In October 2015, idarucizumab, a humanized monoclonal antibody antigen-binding fragment that binds to dabigatran, received expedited approval from the Food and Drug Administration for use in the United States, and other reversal agents are in development.
When all else fails to prevent strokes, Robyn Macsata, MD, chief of Vascular Surgery at the DCVAMC, gets involved.
“I treat the end stage,” Macsata said. “But when it comes to a stroke, a lot of the problem is what’s done is done.”
If the clot has gone to the leg or the arm, she can work to fish that clot out, though the patient could still lose a limb. If the clot travels through other blood vessels, it could put a patient’s intestines at risk.
“When it goes to the brain, it’s very difficult,” Macsata explained. “You can’t do surgery to get rid of the clot. What they do is put them on a more powerful blood thinner.”
- Dodson JA, Petrone A, Gagnon DR, Tinetti ME, Krumholz HM, Gaziano JM. Incidence and Determinants of Traumatic Intracranial Bleeding Among Older Veterans Receiving Warfarin for Atrial Fibrillation. 1Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York
2Veterans Affairs New York Harbor Healthcare System, New York
3Massachusetts Veterans Epidemiology Research and Information Center, Veterans Affairs Boston Healthcare System, Boston
4Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts
5Section of Geriatrics, Department of Medicine, Yale School of Medicine, New Haven, Connecticut
6Department of Chronic Disease Epidemiology, Yale School of Public Health, New Haven, Connecticut
7Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut
8Center for Outcomes Research and Evaluation, Yale–New Haven Hospital, New Haven, Connecticut
9Robert Wood Johnson Foundation Clinical Scholars Program, Yale School of Medicine, New Haven, Connecticut
10Department of Health Policy and Administration, Yale School of Public Health, New Haven, Connecticut 11Division of Aging, Department of Medicine, Brigham and Women’s Hospital/Harvard Medical School, Boston Massachusetts, JAMA Cardiol. Published online March 09, 2016. doi:10.1001/jamacardio.2015.0345
- Ashburner JM, Go AS, Chang Y, Fang MC, Fredman L, Applebaum KM, Singer DE. Effect of Diabetes and Glycemic Control on Ischemic Stroke Risk in AF Patients:ATRIA Study. J Am Coll Cardiol. 2016 Jan 26;67(3):239-47. doi:10.1016/j.jacc.2015.10.080. PubMed PMID: 26796386; PubMed Central PMCID:PMC4724056.
- Dodson JA, Petrone A, Gagnon DR, Tinetti ME, Krumholz HM, Gaziano JM. Abstract 17598: More Than One in Five Older Veterans are Hospitalized for Bleeding Following Initiation of Warfarin for Atrial Fibrillation. Circulation. 2015;132:Suppl 3 A17598.